1. Field of the Invention
The present invention relates to an image scanning apparatus. More particularly, the present invention relates to a scanner module using a light emitting diode as a light source and an image scanning apparatus employing the same.
2. Description of the Related Art
In general, a scanner module is employed in an image scanning apparatus used for a scanner, a copy machine, a facsimile, or a multi-functional peripheral. The scanner module is installed below a manuscript board of the image scanning apparatus to convert image information into an electric signal by reading the image information of the object loaded on the manuscript board.
Such a scanner module includes a light source generating light, an image sensor receiving light reflected from an object to generate an electric signal based on the light, a reflection mirror, a condenser lens, etc., in which the reflection mirror and the condenser lens are aligned in an optical path formed between the light source and the image sensor. A linear light source, such as a CCFL (cold cathode fluorescent lamp) or a xenon lamp, has been used as a light source for a scanner module employed in a conventional image scanning apparatus.
However, in the case of the CCFL, an initial start-up time exceeds 30 seconds so that an initial scan operation is delayed. In addition, since the CCFL contains Hg, it may cause environmental problem. Further, gas activation is lowered in the lower temperature condition so that the image quality may be degraded. In the case of the xenon lamp, the image quality may be degraded due to high-temperature heat generated from the xenon lamp. In addition, the xenon lamp represents low price competitiveness due to the high price of the xenon lamp.
For this reason, recently, an image scanning apparatus using a point light source, such as a light emitting diode, has been suggested. The image scanning apparatus includes a light guide member for guiding light generated from the point light source. According to the above image scanning apparatus, the point light source may serve as a linear light source by diffusing light in the width direction of an object through the light guide member.
As shown in FIG. 1, a light guide member 2 employed in a conventional image scanning apparatus has a predetermined width in an image scan direction of a scanner module and a predetermined length in a sub-scan direction that is perpendicular to the image scan direction. In addition, the light guide member 2 includes an exit surface 2a facing the object, a reflective surface 2b formed in opposition to the output surface 2a to reflect and diffuse the light generated from a light source 1, and a guide surface 2c formed at both sides of the light guide member 2 to connect the exit surface 2a to the reflective surface 2b and inclined relative to the reflective surface 2b such that the light reflected from the reflective surface 2b can be reflected again toward the exit surface 2c of the light guide member 2.
As shown in FIG. 2, the reflective surface 2b of the light guide member 2 employed in the conventional image scanning apparatus has a plurality of reflective grooves 2d, which extend widthwise along the light guide member 2 in parallel to each other, so that the light generated from the light source 1 is reflected and diffused by the reflective surface 2b and then guided toward the exit surface 2a of the light guide member 2. FIG. 3 shows distribution of light, which is irradiated onto a manuscript surface from the light guide member 2, in the image scan direction.